The error tells me you have something set to expect a variable name BUT you are passing it a command.

I actually see several problems.

The Variable User::TruncateTable is incorrectly formed. Use the expressions of the variable to set it to that truncate statement, the value of the variable should be the actual statement that it calculates NOT the formula to get there.

The next problem is you are using BOTH variables and expressions on the execute task, take out the expression OR change the type to something else and let the expression feed it.

CEWII